Bug report

Bug summary

I am updating a line plot. There is an event trigger that starts this updating. If the trigger came from the figure that contains the plot, everything is fine. However, if the trigger came from another figure, then weird results happen: the line that's been updated appears to leave its trace uncleared.

Code for reproduction

import matplotlib.pyplot as plt
import numpy as np

def onclick(event):

    for ii in np.linspace(0., np.pi, 100):
        y1 = y * np.sin(ii)
        line1.set_ydata(y1)
        ax.draw_artist(line1)
        line2.set_ydata(-y1)
        ax2.draw_artist(line2)
        ax2.set_ylim(y1.min(), y1.max())
        fig.canvas.update()
        plt.pause(0.1)


x = np.linspace(0., 2*np.pi, 100)
y = np.sin(x)

fig = plt.figure()
ax = fig.add_subplot(1, 2, 1)
line1 = ax.plot(x, y)[0]

ax2 = fig.add_subplot(1, 2, 2)
line2 = ax2.plot(x, y)[0]


fig2 = plt.figure()

cid = fig2.canvas.mpl_connect('button_press_event', onclick)
# cid = fig.canvas.mpl_connect('button_press_event', onclick)

plt.show()

Actual outcome

Expected outcome

Not the many curves saw in the above figure, just one curve being updated in each cycle. In the code snippet, if use

cid = fig.canvas.mpl_connect('button_press_event', onclick)

then it works as intended.

Also note, if you resize the plot, or save it as figure, then all the residue curves will be gone.

Matplotlib version

• Operating system: windows
• Matplotlib version: 2.0.0
• Matplotlib backend (print(matplotlib.get_backend())): Qt4Agg
• Python version: 2.7
• Jupyter version (if applicable):
• Other libraries: